The Experts below are selected from a list of 35088 Experts worldwide ranked by ideXlab platform
Chihaya Adachi - One of the best experts on this subject based on the ideXlab platform.
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afterglow organic Light Emitting Diode
Advanced Materials, 2016Co-Authors: Ryota Kabe, Chihaya Adachi, Naoto Notsuka, Kou YoshidaAbstract:An afterglow organic Light-Emitting Diode (OLED) that displays electroluminescence with long transient decay after it is turned off is demonstrated. This OLED exhibits blue and green dual emission originating from fluorescence and phosphorescence, respectively. A phosphorescence lifetime of 4.3 s is achieved.
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a highly luminescent spiro anthracenone based organic Light Emitting Diode exhibiting thermally activated delayed fluorescence
Chemical Communications, 2013Co-Authors: Keiro Nasu, Chihaya Adachi, Tetsuya Nakagawa, Hiroko Nomura, Chi Jen Lin, Chienhong Cheng, Mei Rurng Tseng, Takuma YasudaAbstract:Efficient thermally activated delayed fluorescence was observed from a spiro-anthracenone derivative (ACRSA). An organic Light-Emitting Diode containing ACRSA exhibited blue-greenish electroluminescence with a maximum external quantum efficiency of 16.5%.
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organic Light Emitting Diode with liquid Emitting layer
Applied Physics Letters, 2009Co-Authors: Chihaya AdachiAbstract:We demonstrate an original organic Light-Emitting Diode (OLED) having a neat liquid host of 9-(2-ethylhexyl)carbazole (EHCz) doped with a guest emitter of 5,6,11,12-tetraphenylnapthacene (rubrene). The device structure is composed of indium tin-oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrenesulphonate)/EHCz:rubrene/Cs2CO3/ITO. We demonstrate that the liquid organic semiconducting layer surely transports charge carriers, leading to electroluminescence from rubrene with the highest external quantum efficiency of ηext=0.03% at a current density of 0.26 mA/cm2. Our demonstration of the liquid-OLEDs will open another possibility of organic semiconductors and Light-Emitting applications.
C Wetzel - One of the best experts on this subject based on the ideXlab platform.
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defect reduced green gainn gan Light Emitting Diode on nanopatterned sapphire
Applied Physics Letters, 2011Co-Authors: Shi You, Mingwei Zhu, Liang Zhao, Wenting Hou, Theeradetch Detchprohm, Y Taniguchi, N Tamura, S Tanaka, C WetzelAbstract:Green GaInN/GaN quantum well Light-Emitting Diode (LED) wafers were grown on nanopatterned c-plane sapphire substrate by metal-organic vapor phase epitaxy. Without roughening the chip surface, such LEDs show triple the Light output over structures on planar sapphire. By quantitative analysis the enhancement was attributed to both, enhanced generation efficiency and extraction. The spectral interference and emission patterns reveal a 58% enhanced Light extraction while photoluminescence reveals a doubling of the internal quantum efficiency. The latter was attributed to a 44% lower threading dislocation density as observed in transmission electron microscopy. The partial Light output power measured from the sapphire side of the unencapsulated nanopatterned substrate LED die reaches 5.2 mW at 525 nm at 100 mA compared to 1.8 mW in the reference LED.
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dislocation analysis in homoepitaxial gainn gan Light Emitting Diode growth
Journal of Crystal Growth, 2007Co-Authors: Theeradetch Detchprohm, Mingwei Zhu, E F Schubert, Y Xia, W Zhao, Lianghong Liu, D Tsvetkov, Drew Hanser, C WetzelAbstract:We demonstrate homoepitaxial growth of GaInN/GaN-based Light Emitting Diodes (LED) on quasi-bulk GaN with an atomically flat polished surface. The threading dislocation densities of the epitaxial layers were 2-5 x 10 8 cm -2 which was one order of magnitude less than those grown on c-plane sapphire substrate. The growth defects introduced during the epitaxial process were also one order of magnitude smaller than those grown on the sapphire substrate. The crystalline quality and the optical properties of the epitaxial layer and device performance were much improved. The optical output power of the Light Emitting Diode increased by more than one order of magnitude compared to those on sapphire substrate.
N Kobayashi - One of the best experts on this subject based on the ideXlab platform.
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milliwatt operation of algan based single quantum well Light Emitting Diode in the ultraviolet region
Applied Physics Letters, 2001Co-Authors: Toshio Nishida, H Saito, N KobayashiAbstract:By introducing a single-quantum-well active layer and a high-Al-content carrier blocking layer, the output power of an AlGaN-based ultraviolet Light-Emitting Diode has been improved by one order of magnitude. Optical output of 1 mW was achieved at the emission peak wavelength of 341–343 nm.
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submilliwatt operation of algan based ultraviolet Light Emitting Diode using short period alloy superlattice
Applied Physics Letters, 2001Co-Authors: Toshio Nishida, H Saito, N KobayashiAbstract:Over 0.1 mW ultraviolet output was achieved by an AlGaN-based Light-Emitting Diode. To realize a highly conductive and ultraviolet-transparent layer, a short-period alloy superlattice was introduced. The device was fabricated on SiC substrate. Low electric resistivity due to the short-period alloy superlattice and the high thermal conductivity of the SiC substrate enabled large current injection of up to 1.7 kA/cm2. The emission was monochromatic band-edge emission about 350 nm in wavelength without significant D–A and/or deep emissions.
Fred E. Schubert - One of the best experts on this subject based on the ideXlab platform.
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high output power density from gan based two dimensional nanorod Light Emitting Diode arrays
Applied Physics Letters, 2009Co-Authors: Ya-ju Lee, Shing-chung Wang, Hao-chung Kuo, Jong Kyu Kim, Shawnyu Lin, Chinghua Chiu, Sameer Chhajed, Fred E. SchubertAbstract:Here we propose and realize a scheme for making a direct contact to a two-dimensional nanorod Light-Emitting Diode (LED) array using the oblique-angle deposition approach. And, more importantly, we demonstrate highly efficient electrical carrier injection into the nanorods. As a result, we show that at a 20 mA dc current injection, the Light output power density of our nanorod LED array is 3700 mW cm−2. More general, this contact scheme will pave the ways for making direct contacts to other kinds of nanoscale optoelectronic devices.
Rongjun Xie - One of the best experts on this subject based on the ideXlab platform.
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extrahigh color rendering white Light Emitting Diode lamps using oxynitride and nitride phosphors excited by blue Light Emitting Diode
Applied Physics Letters, 2007Co-Authors: Naoki Kimura, Ken Sakuma, Naoto Hirosaki, Syunichiro Hirafune, Kenichiro Asano, Rongjun XieAbstract:The blue-Light-excitation-type white Light-Emitting Diode (LED) lamps are considered to be very suitable for Lighting for art objects, shop window displays, and medical applications because they do not give infrared ray and ultraviolet ray. But their color rendering indices are needed to be improved for such applications. In this letter, the authors have fabricated white LED lamps with a broad range of color temperatures, and realized extrahigh color rendering index Ra values of 95–98 in them, using four oxynitride/nitride phosphors and a blue LED die. It means UV LED die is not always necessary for high color rendering white LED lamps. The luminous efficacies of white LED lamps are 28–35lm∕W, which are sufficiently high for extremely high color rendering white LED lamps.
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warm white Light Emitting Diode with yellowish orange sialon ceramic phosphor
Optics Letters, 2004Co-Authors: Ken Sakuma, Koji Omichi, Naoki Kimura, Masakazu Ohashi, Daiichiro Tanaka, Naoto Hirosaki, Yoshinobu Yamamoto, Rongjun Xie, Takayuki SuehiroAbstract:A warm-white Light-Emitting Diode (LED) without blending of different kinds of phosphors is demonstrated. An approach that consists of a blue LED chip and a wavelength-conversion phosphor is carried out. The phosphor is a newly developed yellowish orange CaEuSiAlON ceramic phosphor with high efficiency. The CIE1931 chromaticity coordinates x,y are (0.458, 0.414), the color temperature is 2750 K, and the luminous efficacy of this LED is 25.9 lm/W at room temperature and with a forward-bias current of 20 mA. The chromaticity of the assembled LED is more thermally stable than that of a LED with a conventional oxide phosphor (YAG:Ce) because of the better thermal stability of the oxynitride phosphor.
